The 19th century was a heyday for poisoning in Great Britain, particularly for those inclined to arsenic, which was cheap, plentiful, fatal in tiny doses and readily available in most apothecaries. To get it, all one had to do was say one was troubled by rats.

Sandra Hempel’s lively The Inheritor’s Powder uses an intriguing murder case to explore the use and effects of arsenic and other poisons — not to mention the new field of forensic toxicology that grew up in response to the many cases of those accused of poisoning their nearest and dearest.

At the center of the book is the 1833 death of George Bodle, a wealthy farmer who lived in a quiet village 10 miles from London. Bodle, along with other members of his family and servants, was sickened by coffee that turned out to be laced with arsenic. The others — who drank less coffee and were more inclined to follow medical advice — recovered; Bodle did not.

Chief among the suspects was Bodle’s grandson “Young John,” a well-dressed, unemployed wastrel who devoted much of his time to flirting with the farm maids.

The sickness and death might not have been recognized as arsenic poisoning if squabbling family members hadn’t started pointing fingers at one another. Arsenic mimics several diseases: food poisoning, malaria, dysentery, and, particularly, cholera — a disease that killed 32,000 people in Britain in the 1830s.

Delving into court and county records and contemporary newspaper accounts, Hempel reconstructs the investigation and trial of Young John, who was ultimately accused of the murder.

It’s a tale that involves a policeman who carries the evidence around for an extended pub crawl, allowing his friends to play with the arsenic; a newly appointed, 24-year-old coroner with no medical experience; and an inquest carried out in a bar.

The hero of the story is James Marsh, a chemistry assistant to scientist Michael Faraday and an expert witness for the prosecution in the case. Marsh developed a test for arsenic that continued to be used for the next century and a half.

Hempel, a British medical journalist, relishes the details of the toxicological mysteries she investigates and describes them in vividly colloquial language. The effects of slow arsenic poisoning, she notes, are “truly the stuff to frighten the horses,” and arsenic’s “shilly-shallying” timetable makes it difficult for a poisoner to figure out how quickly it will bring about a death.

Her explorations of medical and forensic history are as fascinating as the story of the Bodles, which has all the elements of a classic whodunit, including a surprise ending.